Researchers at Wake Forest University School of Medicine in North Carolina and the University of East Anglia in England found that long-term use of a popular class of diabetic drugs – thiazolidinediones – doubles the risk of fractures in women with type 2 diabetes. The findings were published in the Canadian Medical Association Journal.

The researchers set out to evaluate the magnitude of the association between TZDs and fracture risk. TZDs are oral medications given to both men and women to lower blood sugar. The increased fracture risk, however, is associated primarily with women. Researchers reviewed 10 previously completed trials that lasted at least one year and included nearly 14,000 participants.

According to the results, if TZDs are used by elderly, postmenopausal women (around 70 years old) with type 2 diabetes for one year, one additional fracture would occur among every 21 women. If they are used by younger women (around 56 years old), one additional fracture would occur among every 55 women.

The “relatively modest benefits of thiazolidinediones must be balanced against their significant long-term effects on bone and the cardiovascular system,” wrote the researchers.